20220825

한 번에 끝내는 Java/Spring 웹 개발 마스터

1) Thread 우선순위

package ch21;

class PriorityThread extends Thread {

	public void run() {

		int sum = 0;

		Thread t = Thread.currentThread();
		System.out.println(t + "start");

		for (int i = 0; i <= 1000000; i++) {

			sum += i;
		}

		System.out.println(t.getPriority() + "end");
	}
}

public class PriorityTest {

	public static void main(String[] args) {

		int i;
		// for(i=Thread.MIN_PRIORITY; i<= Thread.MAX_PRIORITY; i++){

		PriorityThread pt1 = new PriorityThread();
		PriorityThread pt2 = new PriorityThread();
		PriorityThread pt3 = new PriorityThread();

		pt1.setPriority(Thread.MIN_PRIORITY);
		pt1.setPriority(Thread.NORM_PRIORITY);
		pt1.setPriority(Thread.MAX_PRIORITY);

		pt1.start();
		pt2.start();
		pt3.start();
	}
}

• 우선 순위가 높은 Thread가 CPU의 배분을 받을 확률이 높다
• Thread.MIN_PRIORITY(=1) ~ Thread.MAX_PRIORITY(=10)

2) join()

package ch21;

public class JoinTest extends Thread {

	int start;
	int end;
	int total = 0;
	
	public JoinTest(int start, int end) {
		this.start = start;
		this.end = end;
	}
	
	public void run() {
	
		int i; 
		
		for(i=start; i<=end; i++) {
			
			total += i;
		}
	}
	
	public static void main(String[] args) {
		
		JoinTest join1 = new JoinTest(1, 50);
		JoinTest join2 = new JoinTest(51, 100);
		
		join1.start();
		join2.start();
		
		try{
			join1.join();
			join2.join();
			
		}catch (InterruptedException e) {
			System.out.println(e);
		}
		
		int lastTotal = join1.total + join2.total;
		
		System.out.println("join1.total = " + join1.total);
		System.out.println("join2.total = " +join2.total);
		
		System.out.println("lastTotal = " + lastTotal);
	}
}

• 동시에 두 개 이상의 Thread가 실행 될 때 다른 Thread의 결과를 참조 하여 실행해야 하는 경우 join() 함수를 사용